Telescoped ammunition typically includes a propellant charge having an axial bore or cavity, a projectile housed entirely within the axial cavity of the propellant charge and, optionally, a case around the propellant charge. When a telescoped round of ammunition is loaded into the chamber of a gun, the projectile, being housed in the cavity of the propellant charge, is not seated directly in the chamber/barrel of the gun, as is the projectile of a round of conventional ammunition when loaded in a gun chamber. When the telescoped round is fired, the projectile is forced forward into the barrel of the gun and at that time becomes seated in the barrel. More specifically, when the telescoped round is fired, a primer ignites a booster charge which causes forward motion of a piston located within the axial cavity of the propellant charge. The piston accelerates the projectile toward the gun barrel. The projectile moves at a relatively low velocity during this boost phase. Projectiles with short piston strokes and also long ogive projectiles, particularly projectiles having a center of gravity forward of the driving band, may be unstable during this boost phase and enter the gun barrel off-center (that is, not concentric with the gun barrel bore). This creates an uneven obturation and poor sealing within the gun barrel bore and may cause the projectile to ballot (oscillate side-to-side) down the gun barrel.
It has been known in the past to employ a so called "bore rider", that is a band, usually plastic, placed over the nose of the projectile. A bore rider, however, may get free of the projectile during firing of the round and enter the gun barrel ahead of the projectile. It may be destroyed in the barrel, in some cases leaving debris in the barrel, or be ejected at the forward end of the gun barrel. Such debris in a gun barrel or in the area of the gun can affect both safety and ammunition efficacy. In addition, in some instances bore riders do not adequately overcome the problem of projectile instability.
It is an object of the present invention to provide a telescoped ammunition round having improved projectile stability during firing. This and additional objects of the invention will be apparent from the following disclosure.